Rawhide, despite it's popularity isn't very good for dogs and is more then likely the cause of the runny stools.
Feed your dog a different treat... but do it in moderation.
Even things like pig ears etc. can give them gas if you give them to much.

There are other factors here such as the sensitivity of your dogs stomach that some of these treats can really throw for a loop.

Either way, stop given the dog rawhide and you should see an improvement.

My old neighbors used to give our dogs rawhide chews and it made our lab's stomach so upset she would get runny poop for days. I think after they finally stopped giving her the rawhide, after we told them numerous times to stop, it took her about a week to get back to regular. I give them bully sticks and they do fine on those.

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